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Fibularis Brevis Muscle Anatomy

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Origin
  • Distal two-thirds of the lateral surface of the fibula
Insertion
  • Tuberosity of the fifth metatarsal
Action
  • Eversion of the foot
  • Weakly assists in plantar flexion
Innervation
  • Superficial fibular (peroneal) nerve (L5, S1)
Blood Supply
  • Fibular (peroneal) artery
  • Anterior tibial artery
Last updated: Estimated Reading Time: 5 min

Location & Overview

The fibularis brevis, which was previously known as the peroneus brevis, is a muscle in the lower leg. This muscle is short and spindle-shaped (fusiform), and it can be found on the lateral (outer) side of the leg. It is one of three fibularis muscles, the others being the fibularis longus and the fibularis tertius. These muscles are called ‘fibularis’ because they are near the fibula bone and also attach to it.[1,2,3]

The fibularis brevis shares space with the fibularis longus in what is known as the lateral compartment of the leg, which is on the outer side of the leg. Sections of the fibularis brevis are positioned somewhat anterior to the fibularis longus, with the proximal and posterior part of the fibularis brevis lying deep to the fibularis longus muscle. Its positioning is demonstrated in the images further down the page.[1,2,3]

The tendon of the fibularis brevis also travels alongside the tendon of the fibularis longus, passing behind the lateral malleolus, a bony bump on the outer ankle. After passing behind the lateral malleolus, it travels anteriorly and inferiorly into a groove on the calcaneus (heel bone), where it continues toward its insertion on the fifth metatarsal, the long bone connected to the little toe.[1,2,3]

fibularis brevis lateral view
Here, we can see the fibularis brevis muscle from a lateral view.
fibularis brevis posterolateral view
Here, we can see the fibularis brevis muscle from a posterolateral view.
fibularis brevis posterior view
Here, we can see the fibularis brevis muscle from a posterior view.
three fibularis muscles (aka peroneus muscles), fibularis longus, fibularis brevis, and fibularis tertius
Here, we can see all three of the fibularis muscles: the fibularis longus, fibularis brevis, and fibularis tertius.

Origin & Insertion

The fibularis brevis originates on the distal two-thirds of the lateral surface of the fibula. This site provides a sturdy base from which the muscle can exert force. The muscle then forms a tendon, which continues past the ankle joint, passing behind the lateral malleolus and through a groove on the calcaneus, to its insertion at the base of the fifth metatarsal, specifically the tuberosity of the fifth metatarsal. This tuberosity is a prominent area located on the lateral side of the base of this bone, providing a leverage point for the muscle’s actions.[1,2,3]

fibularis brevis origin and insertion
Here, we can see the fibularis brevis muscle’s origin marked in red on the fibula’s lateral surface and its insertion marked in blue on the tuberosity of the fifth metatarsal.

Action & Function

The primary action of the fibularis brevis is eversion of the foot, a movement that involves tilting the sole of the foot away from the midline of the body. This action helps maintain balance, especially on uneven terrain, and allows for adaptive changes in the foot’s posture. In addition, the fibularis brevis assists weakly with plantar flexion of the foot at the ankle joint. Plantar flexion refers to the downward movement of the foot away from the leg, a motion seen in exercises such as ‘calf raises’ and during the push-off phase while walking.[1,2,3]

Image of a person demonstrating the movement of foot eversion.
This picture demonstrates foot eversion, which means rotating the foot outward, causing the sole of the foot to turn away from the body. The opposite of eversion is inversion. Eversion is the primary action of the fibularis brevis.
Image of a person demonstrating the movement of foot plantar flexion.
This image shows an example of foot plantar flexion, which involves pointing the foot downward away from the shin. The opposite of plantar flexion is dorsiflexion. The fibularis brevis can weakly assist with plantar flexion.

Innervation

The fibularis brevis is innervated by the superficial fibular (peroneal) nerve, which arises from the spinal roots of L5 and S1. This nerve is responsible for conveying signals from the brain to the muscle for contraction and transmitting sensory information from the leg to the central nervous system. The superficial fibular nerve is a terminal branch of the common fibular nerve, and the common fibular nerve is a branch of the sciatic nerve.[1,2,3]

Superficial fibular nerve (aka peroneal nerve)
Here, we can see the superficial fibular nerve highlighted in red. The superficial fibular nerve innervates the fibularis brevis from the nerve roots of L5 and S1. The superficial fibular nerve was previously known as the peroneal nerve.

Blood Supply

Blood is supplied to the fibularis brevis primarily by the fibular (peroneal) artery, particularly its muscular branches. This muscle also receives blood from the anterior tibial artery.[4]

References

  1. [1] Dalley AF II, Agur AMR. Moore’s Clinically Oriented Anatomy. 9th ed. Wolters Kluwer Health; 2022.
  2. [2] Standring S. (2015). Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 41st Edn. Amsterdam: Elsevier
  3. [3] Palastanga N, Soames RW. Anatomy and Human Movement: Structure and Function (Physiotherapy Essentials), 6th ed. Elsevier; 2011. ISBN-13: 978-0702035531.
  4. [4] Basit H, Shah J, Siccardi MA. Anatomy, Bony Pelvis and Lower Limb, Foot Peroneus Brevis Muscle. (Updated 2023 Apr 4). In: StatPearls (Internet). Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK535427/

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